Process for making rubber footwear.



E. A. SAUNDERS. PROCESS FOR MAKING RUBBER FOOTWEAR.

APPLICATION FILED r1113. 24, 1905. zumnwm) 811m. B, 1906.

927,287, Patented July 6, 1909.

5&1.

UNITED STATES PATENT OFFICE.

EMMETTA. SAUN DERS, OF SOUTH BEND, INDIANA.

PROCESS FOR MAKING RUBBER- FOOTWEAR.

Specification of Letters Patent.

Patented m 6-, 1909;

application filed February 84, 1906; Serial No. 347,101. Renewed September 8,1906. Serial No. 383,779. I

To all whom it may concern:

Be it known that I EMME'I'I A. SAUNDERS,

a citizen of the United States, residing in production of improved rubber footwear which, by reason of its seamless character, has none of the disadvantages of a permanently cemented article; and wherein the under parts of the shoes on the one hand and the entire up wars on the other hand possess each the peculiar characteristics best adapted to their own necessities under conditions of use.

Seamless rubber footwear has been hitherto manufactured by building up'the whole boot or shoe on a last and vul'canizing the parts altogether to produce an integral article of manufacture. In some cases this vulcanization takes place by exposure to open heat in a proper oven. In other cases a mold is provided which incloses the entire boot or shoe and wherein it is subjected to simultaneous heat and pressure to accomplish vulcanization.

The present invention aims to overcome certain disadvantages unavoidably incident to both of the above named modes of treatment. These may be stated as follows: The main objection to vulcanizing an entire shoe by open heat in an oven lies in the fact that all green rubber compounds contain more or less moisture andother materials which form expansible gases on being heated. In consequence, when a rubber shoe is vulcanized by open heat these gases open up cells within the rubber walls, giving the whole a more or less spongy texture. The thin parts of the shoe contain less gas-producing fluids than the thicker portions, owing to the greater expressive effect of the form ing rollers or calenders on thin sheets than on thlcker masses. Hence the sponginess developed durin vulcanization 15 not noticeable in these t inner portions, and such lack of solidity as does exist is rather beneficial than otherwise, as it promotes elasticity and liability. The thicker portions of the shoe, owever, containing as they do a greater amount of moisture etc. suffers. greater extioned and hitherto used is also open to ob-' jections. Where the entire shoe is placed in a mold for vulcanization under pressure, the spon iness above mentioned is prevented in t e thicker arts but the softness is also suppressed in t e thinner portions of the shoe. As heretofore mentioned, this softness is beneficial in the thinner walls, and its suppression tends to brittleness in the very parts which must be allowed to yield when the shoe is taken off or put on, and must bend or wrinkle when on the foot. Another important disadvanta e met with in this prior process is that the thicker parts, including the heel, the sole and those portions of the remainder of the shoe in direct contact therewith, require more prolonged action than the uppers. It results from this that either the uppers are overcured during a given treatment, or the aforesaid thicker portions-are not suflicicntly vulcanized. If the uppers are overcured they are hard, inelastic and unyielding and, as the strains of wear on the uppers are pulling and bending strains, quick deterioration is the result. If, on the other hand, the thin u pers are not vulcanized too hard, the t lcker parts at sole and heel are left too soft for resisting the Wear to which they are subjected. This wear takes the form of shock and abrasion, and a tough, hard, relatively unyielding con- ,dition is best in these portions of a boot or shoe.

By the practice of my present invention I am able to roduce a shoe having a soft elastie and plia le texture in the thin walls of the upper portions but free from spongy or cellular structure in those thicker ortions at the bottom of the shoe which are intended to resist shocks and abrasive action.

In carrying out this process I may make use of any desired apparatus whether novel or well known, and an example of suitable t all last shown in the operating position and Fig. 2 is a perspective view of a rubber sole ready for application to a shoe in the mold shown in Fig. 1.

In practicing my improved process I referably proceed as follows: The body 0 the shoe including the inner sole all shown at 1 in Fig. v1,-is built up in the usual manner on a last-2, being constructed of properly sha ed parts temporarily cemented together. he thick outer rubber sole 3 is separately prepared, being either formed green or partly all around thelowenedge of the shoe body.

The form ofsole illustrated is not essential to my invention the see c of which covers the use and application 0 a mere tap sole or of a heel alone. The shoe body and the thick lower part to be applied thereto-having been thus separately prepared, the latter is placed in a mold 5 into which it fits snugly, which mold is combined with means for pressing the shoe body, while still on the last, down onto the sole in said mold. In the illustrative form of apparatus shown in the drawings, this takes the shape of an arch 6 fitted with a screw 7 having a hand wheel 8. The last with the shoe bod upon it is p aced upon the sole 3 so as to t within the upturned edge 4 and the screw 7 is turned down hard u on it. body w en thus forced down into the concave sole when in the mold 5 is to create a pressure between the soft meeting surfaces oints, .and thus the soleis pressed pon t e shoe body, not only on the under surface, but horizontally along the entire length of the upturned edges 4.

In order to carry out my process, the mold must be heated to a proper vulcanizing temperature and this may be accomplished in any manner desired. In the a paratus shown in the drawing the mold 5 is libllow as shown and the heat is supplied by steam entering for instance at 9 and returning at 10.

I have found that the last should be made of metal in order to reduce the best results, as a wooden core or ast is subject to changes in size by weather conditions.

By the means above described there is created a strong continuous pressure which is preserved during the period of vulcanization of the lower shoe body and joined surfaces, or until this process has been carried so far that the material is able of its own resistance to suppress all'formation of sponginess under the further: influence. of heat. When the rubber reaches this last named condition it may be said to be set, and this word is The action of the convexused in that sense in my claims. Thisword is intended to express a sufficient degree of vulcanization to prevent sponginess on ap-' plication of further heat.

Local vulcanization in a mold as above 7d described must be continued at least to such a point as to .set the composition in the whole under part of the shoe before the, mold is taken off. It may be carried further than from my invention.

1s, of course, obvious that removal of the S5 shoe from the mold is not an essential step, as the vulcanizing of the uppersby open heat can be carried out quite as well while the sole is still in the mold. My broader claims are therefore not limited to a process including this step of removal from the mold.

The apparatus whereby my process is carried out forms no part of this invention, as any form of machine appropriate to accomplishment of the steps above described may e employed.

In t e following claims the term sole is intended to cover either the tap sole .or heel or both together and whether extending upwarden the side of the shoe body or not.

What I claim is W), l. The process of making rubber foot wear which consists in building up the article entire of practically uncured material and vulcanizing the same by subjecting the sole 1 and those parts of the upper which are contiguous thereto to longer heating than the remainder of the article, substantially as described.

2. The process of making rubber foot wear which consists in building up the article entire of practically uncured material, partly vulcanizing the sole and those parts of the upper only which are contiguous thereto under pressure in a mold, and then vulcanizing the entire article at-once, substantially as described.

3. The process of making rubber foot wear which consists in building u an article of practically uncured materia .around a last, joining the sole to the uppers by partly vulcanizing said sole and those parts of the uplplers only which are contiguous thereto w e under pressure between substantially unyielding surfaces, and lastly completing the vulcanization of the shoe outside of the mold, substantially as described.

4. The process of making rubber foot wear which consists in applying a wholly or partly green sole to the remainder of the The 80 article before the latter is set, heating the sole and those parts of the uppers only which are contiguous thereto under pressure until they are set, removing the pressure and subjecting the whole article to a vulcanizing temperature, substantially as described.

5. The rocess of makin rubber foot wear whic consists in building up all but the sole in a green state around a proper last, ap lying thereto a wholly or partly green so e, squeezing the sole and those parts of the upperson'ly which are coiit' uous thereto in a mold against the last w fiile applying heat, and, after the parts so acted upon are set, subjecting the whole article outside of the mold to vulcanizing temperature, substantially as described.

6. The process of making rubber foot wear which consists'in building up separately a green body portion on a last and a concave sole wholly or partly green, ap lying said sole to said body portion while 516 latter is still on the last, squeezing the sole in a mold against the bottom and side edges of said body portion while applying vulcanizing heat, and, after the parts so acted upon are set, subjecting the'whole article outside of the mold to vulcanizing temperature, substantially as described.

7. The process of making rubber foot wear which consists in building up the body portion on an unyielding last, joining the sole thereto by partial vulcanization under pressure in a mold, removing the article rom the mold and com leting vulcanization of the whole outside oi the mold, substantially as described.

8. The process of making rubber foot wear which consists in building u an article of practically uncured materia around a metal last, partly vulcanizing the sole and those parts of the upper only which are contiguous thereto while under pressure between metal surfaces and lastly completing the vulcanization of the shoe outside of the mold, substantially as described.

9. The process of making rubber foot wear which consists in forming the uppers of practically uncured material built up around a proper support, placing the structure so formed in contact with the practically uncured surface of the sole, partly vulcanizing the sole and those parts of the uppers only which are contiguous thereto under pressure in a mold b themselves, and then vulcanizing the entire article at once, substantially asdescribed.

EMMETT A. SAUNDERS.

Witnesses:

H. S. MAOKAY, FLORENCE F101;. 

